Concrete joint insert



Nov. 8, 1966 E. E. HAHN 3,283,674

CONCRETE JOINT INSERT Filed March 24, 1964 INVENTOR. me/"an f. Hob/7 United States Patent O 3,283,674 CONCRETE JOINT INSERT Emeran E. Hahn, Overland Park, Kans., assignor, by

mesne assignments, to Clipper Manufacturing Company, Inc., Grandview, Mo., a corporation of Massachusetts Filed Mar. 24, 1964, Ser. No. 354,262 3 Claims. (Cl. 94-18) This invention relates to concrete slab construction, and more particularly, to an insert rfor placement in a mass of green concrete to present fa joint therefor so that a groove or kerf may be formed in the concrete after it has set.

In forming concrete slabs, a kerf is cut in a mass of concrete after it has set and a joint sealer is deposited in the kerf to fill the latter. It has been found that certain aggregates cannot be cut or sawed when the same are green. To overcome this problem strips of material capable of being sawed have been placed either by hand or by machine into a mass of concrete before it has set to define a joint in the mass so that =a blade comprising a part of conventional equipment may be used to form a kent along the joint defined by the strip even though the concrete is green.

Heretofore, the strip has been formed from a fibrous material impregnated with a bituminous substance to render the strip waterproof, as well as to provide a degree of stiffness therefor. However, when the strip is sawed, the bituminous substance in the strip is caused to coat the side walls of the joint so that fa sealant placed in the joint 'after the kerf lis formed, does not adequately adhere to the side walls. Another Iproblem with the use of the aforesaid strips is that the same are quite flexible and, when placed in a mass of concrete, assume an nndulated or wavy configuration or is caused to snake by virtue of various stresses placed on the sides of the strips along their lengths. As a result, it is difficult to -follow the strips during the kerf-forming operations.

Other yproblems which are presented with the use of the aforesaid strips include the fact that the strips tilt to the side after being inserted in a mass of concrete and the fact that the strips tend to move upwardly due to the buoyancy of the strips in a concrete mass.

The present invention provides an insert which overcomes all of the aforesaid problems of inserts heretofore utilized for the foregoing purpose and is directed to a unit having a relatively yrigid base secured to a strip of fibrous material impregnated with -a substance presenting dry fragmentations -when the strip is sawed. Thus, the strip will not snake, tilt, oat upwardly, or cause the side walls of a mass of concrete to be coated with a substance not compatible with conventional sealants and which are used to fill the kerf.

It is, therefore, the primary object of the present invention to provide an insert for use in kerf-forming operations to overcome the problems hereinabove set forth, especially the problem of coating the si-de walls of a concrete slab as a kerf is being formed therein, whereby :a sealant may be deposited in the kerf and properly bonded to the aforesaid side Walls.

Another object of the present invention is the provision of -an insert of the type described which includes a relatively rigid clip clamped to a strip of fibrous material impregnated with a suitable substance permitting dry fragmentation of the strip upon being sawed, the clip having fa density relatively greater than the density of the strip, whereby the clip will provide a suitable anchor for the strip after the insert is placed in a rnass of green concrete to prevent snaking, tilting, or fioating of the strip in a mass of concrete while the latter is setting to a hardened condition.

"ice

Another object of this invention is to provide an insert unit which is simple in construction, economical to produce, `and capable of being handled Without damage thereto prior to and duning the insertion of the same in a mass of flowable concrete.

In the drawing:

FIGURE .l is a fragmentary, side elevational view of the unit made pursuant to the concepts of the present invention and illustrating a fibrous strip clamped by and projecting outwardly from a .relatively rigid clip;

FIG. 2 is a cross-sectional View of the insert taken along line 2-2 of FIG. l;

FIG. 3 is a sectional view of a concrete slab with the insert placed therein and prior to the formation of a kerf in the slab;

FIG. 4 is a view similar to FIG. 3 but illustrating the kerf formed in the slab by removing a portion of the insert; and

FIG. 5 is a View similar to FIGS. 3 and 4 but showing a sealant in the kerf.

An insert for use in kerf-forrning operations is broadly denoted by the numeral 10 rand includes a strip 12 of fibrous material having a pair of opposed faces 14 and 16, and a pair of longitudinal edges 18 and 20. Strip 12 is impregnated with a suitable resin material to waterproof the same and is treated with a material, such as alum or the like, to provide vermin resistance therefor.

Strip 12 is relatively self-sustaining when placed on edge, but is capable of being sawed and thereby reduced in size, either in length or width. The nature of the substances which are impregnated in strip 12 is such as to bind the fibers together and is capable of being sawed fin a manner to present dry fragmentations rather than sticky or wet fragmentations. The reason for this characteristic of strip 12 will be set forth hereinafter.

Insert 10 further includes a transversely U-shaped clip 22 having a bight 24, and a pair of sides 26 integral with bight 24 and extending away therefrom. Clip 22 has a length substantially equal to the length of strip 12 and is preferably formed from a material having spring characteristics, such as roll-formed galvanized steel. The distance between sides 26 is such that when one longitudinal margin of strip 12 is disposed between sides 26 the latter clamp strip 12 therebetween so as to couple strip 12 to clip 22 to form a unitary structure. In this respect, the width of clip 22 is somewhat less than the width of strip 12 so that when edge 20, for instance, is adjacent bight 24, edge 18 is spaced a distance from the outermost longitudinal edges of sides 26.

Each side 26 has a pair of parallel ribs 28 extending longitudinally of clip 22 intermediate the longitudinal edges of the corresponding side 26. A lateral projection or lip 30 extends outwardly from the outermost longitudinal edge of each side 26.

In use, insert 10 is planted or placed into a mass of concrete before the mass has set, and in this respect, insert 10 is especially suitable for use with green concrete which is quite difficult to saw with -conventional kerfforming equipment; as shown in FIG. 3, insert 10 is disposed in a mass 32 of concrete with edge 18 of strip 12 adjacent to but slightly below the upper surface 34 of mass 32. Clip 22 is thus embedded in mass 32 a distance below surface 34 in a manner such that lips 30 and ribs 28 project into mass 32. The placement of insert 10 is facilitated by virtue of the fact that bight 24 serves as a leading edge for insert 10 as the latter is planted in rnass 32. After insert 10 has been properly positioned in mass 32, ribs 28 and 30 prevent tilting and upward floating of insert 10 in mass 32 so that insert 10 is retained in a fixed position. The rigid nature of clip 22 permits ready placement of insert 10 without damaging the same even though strip 12 may be easily broken in half.

Insert may be flush with surface 34 of mass 32 but even if it is below surface 34, it can be easily located after mass 32 is set by virtue of the fact that a narrow crack 36 will be formed in surface 34; During cool weather crack 36 is not formed as quickly as in warm weather.

Nonetheless, crack 36 will be formed and will outline the position of insert 10 in mass 32.

After mass 32 has set, a kerf 38 is formed therein by conventional equpiment passing over surface 34 and removing the upper portion of strip 12 to present an edge or face 40 on the remaining portion of strip 12-spaced a distance below surface 34 as shown in FIG. 4. As mentiioned above, the substances impregnating strip 12 are such as to present dry fragmentations when strip 12 is sawed. The fragmentations are thrown out of the groove or kerf 38 formed in mass 32 by the blade forming the kerf. Thus, the side walls defining kerf 38 are clean inasmuch as none of the fibrous material forming strip 12 or the substances impregnating strip 12 adhere to the side walls. Thus, when a quantity of sealant 42 is deposited in kerf 38 as shown in FIG. 5, sealant 42 will -properly adhere to the side Walls of the kerf to seal the joint between the slabs of concrete on opposed sides of the kerf.

The Width of kerf 38 is preferably at least as great as the thickness of strip 12 so that the upper portion of the latter will be completely removed during the kerfforming operation. The Iwidth of kerf 38 depends upon governmental regulations so that the thickness of strip 12 may be made accordingly. Also, the depth of kerf 38 is governed by the aforesaid regulations and the width of strip 12 is thus made accordingly. 'I'he width of strip 12 is such that the blade forming kerf 38 does not contact clip 22. Although it is preferable to have clip 22 of a metallic material to provide a low center of gravity for insert 10, it is clear that clip 22 may be formed of any other suitable spring-like material, such as plastic or the like.

By using rigid clip 22, insert 10 may be made in relatively long lengths which are not easily broken into small pieces during handling thereof. Also, clip 22 prevents snaking of insert 10 before or after insert 10 has been placed in a mass of concrete. Clip 22 also provides a rigid leading edge so that insert 10 may be easily pressed down into the green concrete. Clip 22 serves to lower the center of gravity of insert 10 so that the latter will remain in an upright position when placed in the concrete. This prevents strip 12 from tilting and thus eliminates a concrete overhang after the kerf is formed, which overhang easily breaks oi quite easily under heavy loads of cars and trucks. Furthermore, when the strip is cut while in a tilted position, the strip is not adequately re- Sides 26 frictionally engage faces 14 and 16 of strip 12 adjacent edge 20 thereof so that no additional secur-V ing means is required to interconnect strip 12 and clip 22. Sides 26 may be easily shifted away from eachother to permit the insertion of strip 12 therebetween. Upon release of sides 26 the same move into frictional engagement with faces 14 and 16 to clamp strip 12.

Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent is:

1. In a concrete joint, an insert for placement into green concrete, said insert comprising:

an elongated, relatively flexible strip of fragmentatious, fibrous material including an impregnation binding the fibers together for dry fragmentation when sawed, said strip having a pair of spaced, upright side surfaces; and a relatively rigid, transversely U-shaped clip extending the length of said stripy andl including a lowermost arcuate bight section and a pair of opposed, upwardly extending legs integral with the bight section, said strip being frictionally clamped between said legs with each leg in engagement with a corresponding surface of said strip and the clip looped over the lowermost marginal edge of Said strip, each leg terminating belowthe upper edge of said strip in lips extending upwardly and outwardly at an angle from the corresponding surface of the strip, said clip being provided with longitudinal extending rib means coextensive with the length of the clip to prevent bending of said insert. 2. An insert as set forth in claim 1 wherein is provided a pair of parallel, outwardly projecting ribs on each leg of said clip.

3. An insert as set forth in claim 2, said clip having a density greater than the density of said strip.

References Cited by the Examiner UNITED STATES PATENTS 1,667,313 4/1928 Galassi 94-18 2,540,251 2/ 1951 Fischer 94'-18 3,052,945 9/ 1962 Cummings 94-51 X FOREIGN PATENTS 1,151,491 8/ 1957 France.

CHARLES E. OCONNELL, Primary Examiner.

JACOB L. NACKENOFF, Examiner. N. C. BYERS, Assistant Examiner. 

